<form name="search_form" method="get" action="<?php echo get_url_by_lang(switch_language($this->uri->segment(1)), 'search')?>">
    <input type="text" name="q" value="<?php echo $this->input->get('q');?>" placeholder="Tìm kiếm ..." />
    <input type="submit" value="Tìm" />
</form>
<div class="clear"></div>